The present invention relates to an exhaust gas recirculation system for an internal combustion engine, and more particularly to a vacuum regulation valve of the system.
An exhaust gas recirculation system is frequently employed as an effective measure of reducing the oxides of nitrogen emitted from an exhaust system in an internal combustion engine, particularly in an automobile.
Such a system is constructed to recirculate a portion of the exhaust gas from the exhaust system into the intake system of the engine so that the maximum combustion temperature can be reduced as a consequence of the dilution of the admitted air-fuel mixture with the recirculated exhaust gas.
To achieve a greater reduction in the oxides of nitrogen with minimal deterioration of automotive driveability, the amount of the recirculated exhaust gas should be proportional to engine air consumption throughout normal operating conditions of the engine.
To attain this object, the conventional exhaust gas recirculation system includes a vacuum regulation valve for regulating the vacuum in the vacuum line of the system before applied to the vacuum operated exhaust gas recirculation valve.
However, the conventional vacuum regulation valve particularly of the type with a compact construction has encountered the drawback that it produces undesirable clattering sounds under certain engine operating conditions, which sounds should be eliminated for quiet engine operation which assures safe driving of the automobile.
It is accordingly an object of the present invention to provide an improved vacuum regulation valve which is free from the drawback inherent in the conventional vacuum regulation valve.
It is another object of the present invention to provide a vacuum regulation valve of a compact construction.